Effects of phosphor distribution and step-index remote configuration on the performance of white light-emitting diodes.
Opt Lett
; 40(12): 2830-3, 2015 Jun 15.
Article
em En
| MEDLINE
| ID: mdl-26076273
ABSTRACT
Phosphor-converted white light-emitting diodes (pc-WLEDs) are fabricated by combining CaSi2O2N2Eu2+ and Ca2Si5N8Eu2+ phosphors with a blue chip. Experimental results demonstrate that placing the red phosphor layer above the yellow one (Y down/R up) yields the highest luminous efficiency, making it the preferable phosphor distribution for pc-WLEDs rather than Y up/R down. This finding suggests that the extent of overlap between the emission spectrum of short-emission-wavelength phosphors and the excitation spectrum of long-emission-wavelength phosphors and their luminous efficacy of radiation should be taken into account simultaneously when studying the optical characteristics of pc-WLEDs. Compared to common pc-WLEDs with silicone gel as the remote layer, the proposed step-index remote configuration exhibits superior luminous efficiency because of reduced total internal reflection and Fresnel loss.
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01-internacional
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MEDLINE
Idioma:
En
Ano de publicação:
2015
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Article